Ok, so back in the winter I saw this girl out with her boyfriend that was absolutely gorgeous. She looks a lot like Kate from Lost. Her bf had a mutual friend with me and ended up sitting at a table with us and brought her along. So technically I met her once... I now have randomly stumbled upon her facebook and she's single, so I had to add her. She accepted the request and I just sent a message saying "Hey you, haven't I met you somewhere, somehow?,etc..." I haven't gotten a response yet, but I don't know if she just doesn't remember me or what. I really want to say something more to her letting her know I'm really interested. Do I compliment her looks yet? I really want to make her laugh somehow so that I don't just come off as some creep.

None of that "Have I" bullshit.

Hey, I met you that one time at XXX! What's good?

Chances are that you already lost. You should have befriended her when you met her. Now another tip is not to add people you don't know. When I get friend requests from people I don't know I can tell that my bitch shield is up and I'm a guy. Imagine what it does to a girl. They're gonna be like who's this creep adding me for no reason. What you want to do next time is send her a message (improve your message also) and wait for her to reply. Then establish some kind of connection by sending a few messages and then add her.

i do this a lot actually, with much success.
i add the girl. if she accepts the friend request then it's on. i message her and say:

"Hey have we met? you looked familiar so i added you =p" (copied that verbatim from the inbox)

they reply usually with something like "no i don't think so"

then i neg a little with "ahh, maybe i'm just going crazy..or maybe you are. who knowss "

they usually respond well to that. from there i just chat them up. flirty, of course.

note that I'm in high school. if you aren't then the attitudes and social behaviors of the girls may be different. also, all the girls i do this to i have 20-100 mutual friends with on facebook. Good luck!